The executives can be paid more. In a system where all firms are worker coops, it would be a much more compressed difference between the least paid and most paid worker in a firm than the absurd pay differences we see today.
A manger in a worker coop has the same decision-making rights as in any company. The difference is that they are democratically accountable to the workers instead of being accountable to the employer, an alien legal party. Essentially, workers hold all voting shares